Removing specific models
The gun and head mesh are in one object.

Press the Tab key to enter edit mode, select one of the vertices of the gun, then use Ctrl + L to select all of the gun's meshes and erase them.

Ctrl + L is the function to select all connected to the currently selected element (vertex, edge, face).

Finally, you will only get the head.

If you want to separate the guns into different objects without erasing them, select the mesh and press the P key.